Simplify the expression. $ (3r^{7}-r^{4}) + (-5r^{7}-6r^{4}-6r^{2} ) $
Solution: Since we are adding polynomials, we can simply remove the parentheses. $3r^{7}-r^{4} - 5r^{7}-6r^{4}-6r^{2}$ Identify like terms. $ {3 r^7} - \color{#DF0030}{ r^4} - {5 r^7} - \color{#DF0030}{6 r^4} - {6 r^2} $ Combine like terms. $ { ( 3 -5 ) r^7} + \color{#DF0030}{ r^4} + { -6 r^2} $ Add the coefficients. $-2r^{7}-7r^{4}-6r^{2}$